I think i understand the basics of this procedure but having not been to indonesia yet i'm unsure on some details. I attemted to process coffee this way once before and ran into some problems. is their any homemade contraption that can be made to hull the coffee when wet? sample huller really doesnt like doing it and destroys the coffee, very few unbroken beans. ended up hulling by hand last time but that takes way to long. I dried on a raised table but guessing this is not the norm for indonesia. coffee took about 3 weeks to dry and ended up tasting rather flat. I want to try again this week but want to make sure i replicate the processing as accurately as possible. some questions:

1) how long is fermentation typical done? with or without water added? based on the sometimes fruity flavors in these coffees i am guessing fairly short times that leave some mucilage on the parchment (semi-washed)

2)what do farmers typically dry on after fermentation? i'm sure this varies a lot but what would be common among quality producers- tarps? patio's? wood floors? is the coffee commonly raked in any manner or just left to dry?

3) how long and to what moisture content do the farmers dry to. i've heard to around 40-50%

4) it's my understanding that only partially dried then the coffee will be bagged and then sold to collectors (at least in Sumatra). how long does the coffee remain bagged for typically before being dried further.

5)once the coffee gets to a collector is it then immediately hulled? at what moisture content? how is it then dried and how long does drying typically take? what moisture content do they dry to? what are they dried on patio's? raised screend?

i'm sure practices vary a lot. much indonesian coffee i have tasted seems like it may have been dried directly on the ground and probably molded during drying. (interestingingly i recently tasted a coffee here in hawaii that was scary looking, severely molded and had almost everything possible wrong with it. so naturally i roasted it and cupped it and it didn't taste to unlike the average sumatra.) but i'm guessing certainly this is not the case with coffees like Blue Batak and other quality wet-hulled coffees from indonesia.

Regarding hulling, it was recommended to me (can't remember who, sorry) to try hulling with a Cuisinart using the rubber dough kneading paddles rather than blades. Because of the considerable time my thumbs were bleeding after the last manual attempt at the house, I intended to try this (dry) with my next batch; however, I'd certainly be game to try it wet with a small batch of yours too!

Back home on Friday and will be on-island for the next couple of weeks.

Good questions. Since my first visit to Sumatra in 2004 I have been fairly obsessed with getting this right, and working with Tony Marsh over the past few months has really brought me a long ways in terms of understanding this process.

As far as equipment goes, the wet-hullers used in Sumatra are said to be modified de-hullers, except with the blades replaced by specially manufactured rubber ones (this is certainly how they look). Rubber parts might certainly help your super breakage issue, although breakage is a big issue for all wet-hullers. Wet-huller operators I have met take great pride in adjusting the machine exactly right, with the smallest possible amount of damage. To answer your numbered questions:

1) fermentation time is all over the place in Sumatra, and ranges from partial with mucilage still attached to fairly complete. Often, I have seen this fermentation take place in a plastic bucket or bag, and washing done in the same bucket or bag in a nearby stream or pool. In the few washing stations that exist, fermentation is complete and coffee fully washed (no attached parchment) with fresh water.

2) Most common drying substrates are concrete patio, asphalt road, or plastic tarps over dirt/gravel. I have never seen coffee dried directly on the ground. I have often seen it turned by rake, this is very very common.

3) The drying percentage is a confusing one. I have heard 40-50% too, but I have also heard 25%. In practice, this varies a lot around Sumatra. I would experiment, I don't think there is any very solid practice. Most operators go by sight anyway, I have heard "you should wet-hull when the bean reaches the color of milk".

4) In my experience, partially-dried wet parchment (anywhere from just-washed to ready to wet-hull) may be bagged, dried a little bit, rebagged, dried again, any number of times between washing and wet-hulling. It may spend hours or days in bags, depending on local practice and market conditions. I don't believe there is any rule of thumb here. By the way, wet parchment is bought and sold by volume measure at this stage, not weight (via a standardized volume measure called a Bambu)

5) Coffee collectors may wet-hull right away (if they feel the coffee is ready) or dry a little while before wet-hulling. Again, the decision of wet-hulling is done by appearance. Just wet-hulled coffee is called "Kopi Labu", or "Pumpkin Coffee", and this coffee is dried, again on concrete, asphalt road, or plastic tarp, until 11-13%.

There is a tremendous amount of local and individual variation on this process, but these are the basics. I have never seen coffee drying directly on the ground, but I 'm sure it happens sometimes. Tony Marsh feels that much of the earthy/mildewy characteristic doesn't come from direct contact with the ground; it instead comes from the fact that immediately after hulling, the kopi labu is very wet and warm, and its protective layers have been stripped away leaving an attractive environment of enzymes, sugars, moisture, etc for ambient microorganisms to set up shop. The enzymatic activity of these microorganisms lend the earthy, forest-floor, even chocolaty characteristics to Sumatran coffee. There is some anecdotal evidence to support this idea, and it seems logical to me. Certainly, the wet-hulling process is responsible for the diminished acidity and increased body of these coffees, since washed coffees from the same areas do not exhibit these characteristics.

I picked 2Kg of cherry today from a few dozen trees at about 1450ft elevation. just finished pulping by hand (my thumbs are a little sore now. could really use a small hand crank pulper) i'm going to ferment overnight in water for about 14-15 hrs. i will rinse and lay out to dry on a covered patio at 1600 ft elevation tomorrow. i'll let it dry for about 2 days raking a couple times a day, then bag for 2 days and re-dry until it seems whitish in color (seems a vague target but we'll see.) and hull. (hope i can do this somehow other than by hand) i will try and take a moisture reading when i hull. hopefully my moisture meter will read that high. i'll dry it to about 12% moisture content. where i'm drying at uninterupted it usually takes 8-10 days to dry washed parchment. tomorrow if i have time i'll try and pick another 2Kg for a control and process the same way except dry it uninterupted to 12% and then hull.

coincidentally i stumbled across the original wet-hull experiment i did back in december or january. thought i roasted all of it but there is still 300g. that one was picked at about 1600ft. i hulled when moisture content was around 35% i beleive that was after 3-4 days of drying (on a glass table out on the lanai) dried to about 11% after 10-12 more days. I'll roast it tomorrow and see how it's cupping now

Peter, if it doesnt taste too faded i'll send it too you along with some other processing methods done from the same trees. after the experiment i'm doing now is done drying i'll send that over to you. does 150g works?

i do wonder how much of the effects of this method are the result of being hulled wet and how much just the interupted prolonged drying. i've noticed a similar flattening of acidity and increase in mouthfeel in washed coffees that took a long time to dry -3 weeks or so in rainy weather. those coffees also took on some slightly vegetal and herbal qualities.

In regard to all your information and ideas that it teach me a lot.Well in my experience directly with the farmers in PNG, I have never seen a farmer drying parchment on the ground but most farmers use woven mats and most of them do well in their drying process.

Only major problems I came across is that while they are waiting for months for the buyers to come and purchase their coffee than that is where it looses the quality. This is because they do not have good storage and there are not enough buyers that come straight to buy their coffee Parchment. Most of you know about the country But I will try to sent you some packets of samples so that you do the testing and cupping.